.banner{
    margin-top: 15px;
    width: 100%;
    height: 400px;
    overflow: hidden;
    position: relative;
}
.arr{
    position: absolute;
    top: 50%;
    margin-top: -25px;
    width: 100%;
    height: 0px;

}
.arr .arr-left,.arr .arr-right{
    font-size: 50px;
    border-radius: 25px;
    text-align: center;
    line-height: 45px;
    width: 50px;
    height: 50px;
    z-index: 10;
    position: relative;
    background: rgba(0,0,0,0.3);
    color: #fff;
}
.banner-box{
    width: 3305px;
}
.banner-item{
    float: left;
    width: 410px;
    height: 410px;
    margin-right: 3px;
}
.banner-item div{
    float: left;
    width: 130px;
    height: 130px;
    padding: 2px;
    box-sizing: content-box;
    overflow: hidden;
}
.banner-item div.big{
    width: 262px;
    height: 264px;
}
.banner-item div img{
    max-height: 100%;
    min-height: 100%;
    min-width:100%;
    max-width: 100%;
    transition: all 0.2s;
}
.banner-item div img:hover{
    transform: scale(1.2);
}